Device can't be added due to ICMP error

I have a device which used to work both ICMP and SNMP for quite a while now. After rebooting it a few days ago it didn’t come back online saying, that ICMP failed. SNMP and syslog are still working for this device. I tried pinging it via SSH from the LibreNMS server successfully. So I deleted it and tried re-adding it, but it still fails saying that ICMP did not respond. Any ideas?

What kind of device is it?

It’s an Dell-labeled KVM console Avocent MergePoint Unity.

Are you making ICMP towards the DNS Record?

I tried re-adding using both the DNS name and the IP address, but both didn’t ran into a timeout.